swift

d4a3be56 - [ConstraintSystem] `trySimplifyToExpr` shouldn't rely on locator being always anchored

[ConstraintSystem] `trySimplifyToExpr` shouldn't rely on locator being always anchored If constraint system is used as part of the declaration checker to e.g. verify generic requirements for a witness, locators are not going to have an anchor. Resolves: [SR-10728](https://bugs.swift.org/browse/SR-10728) Resolves: rdar://problem/50987089 (cherry picked from commit ae5cce4a6adc55d7fb1dc20bf5e50c16df3e300f)